Process and apparatus for producing a barbed spiral

ABSTRACT

A process and apparatus for producing a barbed spiral from a flat metallic barbed strip having a series of barbs and a supporting wire wherein the wire and metallic strip are combined in envelope rollers so that the wire is embedded into a flat metallic strip. At the output of the envelope rollers is a reel for winding the wire supported strip in convolutions so that every other barb of adjacent convolutions can be connected together to form a spiral fence when the assembly is opened in a longitudinal direction. The invention includes a plurality of circumferentially spaced-apart clamping devices which are mounted on a rotary table which rotates synchronously with respect to the reel. There is provided a means for lowering the reel corresponding to the rise of the winding with respect to the rotary table and the output of the envelope rollers. Fingers are also provided for compressing the convolutions on the reel as they are being gathered.

Uhl

[ Nov. 4, 1975 PROCESS AND APPARATUS FOR PRODUCING A BARBED SPIRAL [75] Inventor: Siegfried Uhl, Augsburg, Germany [22] Filed: Sept. 23, 1974 [21] App]. No.: 508,133

[30] Foreign Application Priority Data Sept. 28, 1973 Germany 2348714 52 us. or 140/4; 140/58 51 Int. (:1. B21F 27/08 58 Field of Search 140 4, 11,58, 66, 59,

[56] References Cited UNITED STATES PATENTS Sieffert 256/2 Il/l964 Primary ExaminerLowell A. Larson Attorney, Agent, or FirmAllison C. Collard [57] ABSTRACT A process and apparatus for producing a barbed spiral from a flat metallic barbed strip having a series of barbs and a supporting wire wherein the wire and metallic strip are combined in envelope rollers so that the wire is embedded into a flat metallic strip. At the output of the envelope rollers is a reel for winding the wire supported strip in convolutions so that every other barb of adjacent convolutions can be connected together to form a spiral fence when the assembly is opened in a longitudinal direction. The invention includes a plurality of circumferentially spaced-apart clamping devices which are mounted on a rotary table which rotates synchronously with respect to the reel. There is provided a means for lowering the reel corresponding to the rise of the winding with respect to the rotary table and the output of the envelope rollers. Fingers are also provided for compressing the convolutions on the reel as they are being gathered.

14 Claims, 14 Drawing Figures PfitfiIlt Nov. 4, 1975 Sheet 1 of 8 US. Patent Nov. 4, 1975 Sheet 2 of8 3,916,958

Fig. 5

Fig. 6

U.S. Patent Nov. 4, 1975 Sheet 3 of8 3,916,958

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I]: m/ N o Qfi 8 Q Wt T HE O O O 2 Sheet 5 of 8 3,916,958

US. Patent Nov. 4, 1975 Fig. 10a

US. Patent Nov. 4, 1975 Sheet7of 8 3,916,958

U.S. Patent Nov.4, 1975 Sheet 8 of8 3,916,958

oo i comm? ooww ooh: oomo comm ooom 0C5 comb comm ooqm oomq comm ochw 609 com PROCESS AND APPARATUS FOR PRODUCING A BARBED SPIRAL This invention relates to a process and apparatus for producing a barbed spiral from a flat metallic barbed strip. The strip envelops a supporting wire with portions of its strip surface by winding the barbed strip in convolutions juxtaposed in the longitudinal direction of the spiral on to a reel and connecting adjacent convolutions of the spiral at an uneven number of e.g. five points uniformly distributed over the periphery of the spiral so that in accordianlike manner, the spiral is extendable to a greater or lesser extent in the direction of its longitudinal axis (US. Pat. No. 2,908,484).

In the prior art, the enveloping of the supporting wire by the flat barbed strip, its winding to form a spiral, and its connection to adjacent convolutions have taken place in three separate operations. This leads to nonproductive time during travel between the individual working stations, and requires a number of operating staff corresponding to the number of working stations.

An object of the invention is to provide an automatic machine so that the manufacturing operations can be performed automatically in a single machine. The invention not only relates to the purely mechanical combination of the individual known Working stations but also to a way of combining them so that several operations can be performed together in interaction. In particular, the invention applies to the winding to fonn a spiral, and its connection to adjacent convolutions at five or seven points. The connections are carried out on convolutions of the finished spiral so that the connecting members are each fitted at particular points in one row of the different layers, and alternate from row to row. The combination of the steps of connecting with winding require a different operation, so that the convolutions to be connected are only engaged as they are being formed, and must be placed to such an extent that connection can take place.

According to the invention, this problem is solved in that when the strip is wound up, it is connected with the final convolution at the next point of the connecting member spacing. Therefore, with a spacing of five, this leads to an interchange between every two and every three connecting member points, between every two convolution layers. The barbed strip is wound on to the strip surface at right angles with respect to the spiral longitudinal axis. Portions of the barbed strip cover one another in the longitudinal direction of the spiral, and connecting members are inserted in a gap between the portions of the barbed strip carrying the barbs. The connection process requires a certain time and requires a concomitant movement of the barbed strip.

In a further embodiment of the inventive concept,

there is provided an apparatus for performing the pro- 1 cess having delivery spool for the barbed strip, a delivery spool for the wire, and a pair of rollers for channelling the barbed strip so that the wire is received in channel rollers and enveloped with the barbed'strip. A reel is provided for winding up the strip, and rotates continuously with the running speed of the strip with slippage. A synchronously rotating rotary table surrounds the reel so that on the rotary table, there are disposed a number of radial clamping devices corresponding to the number of connecting member points for connection of the convolutions of the spiral. Since each of the five clamping devices only has to operate once 2 every two revolutions, there is adequate time for the connecting process to take place. The winding capacity of the reel is an integral multiple of the spacing of the barbed strip portions carrying the barbs divided by the number of clamping devices. 1

The reel is formed by coaxially positioned web ribs which are distributed over its periphery in such a way that they engage in the gaps between the barbed strip portions carrying the barbs. In order to keep the feed-in point of the strip stationary with respect to the rotary table with its clamping devices, it is preferably to have the reel lowered corresponding to the rise in the winding in proportion to the rotary table and feed-in point.

Therefore the relationship between the level at the start of winding, and the feed-in point and rotary table re!v mains constant.

In order to engage with the lower clamping device leg if between the lower convolution (which is to be connected with a convolution passing above it) andthe connected convolution below it on the rotary table, between each of the clamping devices, a finger is pro-. vided which can be pivoted into and out of the winding circle of the reel. This in and out pivoting preferably takes place in a plane containing the rotational axis of the reel. Therefore, the finger according to the invention is carried by a swivel arm, and has a spring catch with a top abutment which can bemoved permanentlyback on to the steel strip on swivelling back its swivel arm. The fingers are arranged behind and adjacent to each clamping device in the rotational direction.

The clamping device according to the invention has a pair of legs whose power arms are coupled to expending arms which are articulated to a common fork located on a hollow piston rod. On both sides of the piston, a pressure medium such as compressed air can act so that the two clamping device leg spindles are mounted on one head. The head is located on a sliding bar which projects out of'the hollow piston rod and is under the force action of a compressing spring supported on the fork. Between the fork is a slide which is arranged at the front and has a jaw for the barbed strip springs. The slide is extendable in a sliding guide fixed to the cylinder body of the piston in a stroke limited by stop members so that after its passage, and after overcoming the tension of the springs, the expanding arms then permit the clamping device legs to perform the connection.

Other objects and features of the present invention will become apparent from the following detailed description when taken in connection with the accompanying drawings which disclose several embodiments of the invention. It is to be understood that the drawings are designed for the purposes of illustration only, and are not intended as a definition of the limits and scope of the invention disclosed.

In the drawings, wherein similar reference numerals denote similar elements throughout the several views:

FIG. 1 is a plan view of the barbed strip;

FIG. 2 is a cross sectional view of the barbed strip in the unconnected area;

FIG. 3 shows the barbed strip incross section at a connection point;

FIG. 4 shows the winding of the connected spirals;

FIG. 5 is a plan view of the apparatus;

FIG. 6 is an elevation view of the apparatus;

FIG. 7 is an" elevation view of the clamping device;

FIG. 8 is the clamping device in cross section;

FIG. 9 shows the clamping device in cross section in a different position; I

FIG. 10 shows a plan view of the clamping device with a connecting member feed;

FIG. 11 shows the clamping device in a front view with the connecting member supply and the magazine for the connecting members;

FIG. 12 shows the hold down device partly in section; and

FIG. 13 shows the timing schedule.

In FIGS. 1 and 2, a flat steel strip 11 is provided with recesses at its two edges leaving pointed barbs 12. A narrow strip bridge 14 is left between each pair of facing recesses. Over the complete length of this strip, there is a central channel on one side enabling a supporting wire 13 made from spring steel to be embedded therein. Embedding is followed by beading of the strip bridge portions 14, so that the supporting wire 13 is firmly enveloped.

When the formed barbed strip is wound onto a reel, it is wound into a spiral whose winding can be seen in FIG. 4. In FIG. 4, a connection with connecting members 15 (of FIG. 3) is performed so that at every second connecting point of the five connecting stations, a connection takes place at each adjacent convolution on the next point of spacings I, II, III, IV and V. Therefore, convolutions l and 2 are connected together at spacings I, III and V, while convolutions 2 and 3 are connected together at spacings II and IV. In FIG. 4, this is shown up to convolution 10.

In FIGS. 5 and 6, the automatic machine has a delivery spool 16 for the barbed strip which is supplied via a guide roller 17 to a pair of rollers 18 for channelling the barbed strip to form a channel. The machine also has a delivery spool 19 for the wire which at exit 21, is fed laterally from above via a stumpet pipe 20 into the channel of the barbed strip. Rollers 22 serve to envelop the wire with the barbed strip.

The formed barbed strip is supplied via a guide tube 23 to a reel 24 which continuously rotates with the running speed of the strip in rotational direction D. The reel is driven together with rollers 22 e.g. by means of hydraulic motors which are supplied by a common oil pump. By means of a choke in the intake to the hydraulic motor for rollers 22, there is a somewhat larger torque applied to the reel so that relative to the rollers 22, reel 24 rotates with slippage and draws the barbed strip from rollers 22. The pair of rollers 18 is not driven. The barbed strip is drawn through rollers 18 by rollers 22.

The end of guide tube 23 defines the feed-in point 25. The beginning edge of the strip is fixed to reel 24 at 26. It is fixed so that the barbed strip with its strip surface According to a spacing of five of the winding periphery, each two adjacent web ribs 27 are closely paired together in order to secure connecting members 15 between them to superimpose coated convolutions of the barbed strip. Facing the spacing of each pair of web ribs 27 is a clamping device 28 which is located on a rotary table 29 surrounding reel 24 and rotating synchronously therewith.

In FIGS. 7 to 11, each clamping device 28 has two legs 30 with mountings 130 for connecting member 15 on the particular load arm, whose associated power arm 31 is located on the other side of a pivot 32 in each case. At the other end 33 of each power arm 31 is articulated an expanding lever 34 which at pivot 35 is supported in articulated manner to a fork 36. Fork 36 is located at the end of a hollow piston rod 37 which can be extended and retracted by a piston 38 located in a cylindner 39. A pressure medium such as compressed air can be applied to both sides of piston 38. In the hollow piston rod 37 is located a projecting sliding bar 40 with a head 41. The underside of the head engages a spring 42 supported on fork 36. Head 41 is fork-like and under the tension of spring 42, and is applied with its web fixed to sliding bar 40 between the converging area 131 of clamping device legs 31 so as to hold these apart. On the forks of head 41 are also contained the bearings 32 for clamping device legs 30 and 31, and flanked on both sides by side plates 43. The free front end of plates 43 embrace head 41 and form a collecting 30 jaw 44. At their rear end, facing cylinder 39, they can is wound on horizontally at right angles to the rotational axis of reel 24 which thus becomes the spiral longitudinal axis as indicated by the curvature shown in FIG. 1. The winding contour of the reel is formed by the outer edges of coaxially arranged web ribs 27 which are distributed over the periphery in such a way that they engage in the gaps between the barbed strip portions carrying the barbs providedthat there has been an appropriate fixing of the starting edge of the strip at 26. The winding periphery of the reel represents an integral multiple of the spacing of the barbed strip portions carrying the barbs which can be divided by five. It is thereby ensured that the barbed strip portions carrying the barbs, cover one another in the longitudinal direction of the spiral.

slide in slide guides 45 firmly connected with cylinder 39. The connection between head 41 and side plates 43 is made by a frictional connection using a total of four relatively weak compression springs 46 which are supported in blind holes on the face of head 41 and on the back of jaw 44. The springs push forward jaw 44 and side plates 43 on slide guides 45. During the return stroke, a pair of bolts 48 projecting on either side from head 41 engage an oblong hole 47 on each side plate 43 which return the side plates 43 with jaw 44 by positive locking. Slide guides 45 carry adjustable abutments 49 which serve to limit the extent of movement of side plates 43 with their counter-abutments 50.

When piston 38 is extended, the clamping device legs in the position shown in FIGS. 7 and 8 are extended into the position of FIG. 9 since under the tension of spring 42, head 41 and fork 36 do not change in relative position. Load arms 30 then move forward with a connectng member 15 which previously has been laterally fed into their mountings 130. Under the tension of springs 46, collecting jaw 44 and side plates 43 on slide guides 45 follow the forward movement of head 41 until abutments 50 strike against abutments 49 as shown in FIG. 9. During the last part of the abovedescribed extension movement, jaw 44 has received the two uppermost convolutions of the barbed spiral to be connected as indicated in FIG. 12. The barbed strip portions carrying the barbs are then located on the bottom of collecting jaw 44. Adjustable abutments 49 are set so that the barbed strip is lightly pressed against web ribs 27' of reel 24 to be fixed in a position which is advantageous for connecting purposes.

Since piston 38 can still be advanced further as can be seen in FIG. 9, it moves without transition into the following second phase of its extension movement wherein the slide guide 43 with collecting jaw 44 remains stationary. Due to the compression of springs 46, head 41 moves further forward so that spring 42 holds the clamping device arms in their original angular position. Connecting members 15 located in mounting 130 between load arms 30, are advanced forward between the portions carrying the barbs up to the two barbed spiral convolutions to be connected. The face of the fork portions of head 41 assumes its end position on the back of collecting jaw 44 (FIG. a).

In the third phase of the extension movement of piston 38 (FIG. 10b) under the compression of spring 42, fork 36 permits expanding levers 34 and force arms 31 to spread apart thereby compressing the load arms 30 with the force necessary for closing connecting member so that connecting member 15 and the barbed spiral convolutions to be connected together are closed. .j

The clamping device is retracted by operating piston 39 on the piston rod side so that the above-described steps take place in the reverse sequence.

The individual connecting members 15 are supplied to clamping device 28 laterally through an opening 51 in one of the two side plates 43. In the inoperative position of clamping device 28, opening 51 is aligned with connecting member mountings 130. Channel 52 is firmly connected to the side plate and bent back in the moving direction of clamping device 28. The individual connection members 15 are introduced into channel 52 by means of a plunger 53 movably guided on cylinder 39. The plunger is resiliently sprung in the return stroke direction of clamping device 28. Plunger 53 enters channel 52 from behind, and advances the connecting members located in channel 52, so that in each case, the furthest forward connecting member 15 is moved into mountings 130 when during the return stroke, opening 51 covers the then empty connecting member mountings 130. Connecting members 15 are in turn supplied to channel 52 from a magazine 54. The connecting members are kept in stock in a plurality of magazine parts under spring tension in a systematic spatially correct position. The maximum insertion depth of plunger 53 into channel 52 is set so that in the furthest extended position of clamping device 28 between the front end of plunger 53 and the final connecting member in channel 52, a gap is formed having the width of at least one connecting member so that a further connecting member can be inserted from below into the gap from magazine 54.

Connecting members 15 are sorted into the spatially correct symmetrical position in magazine 54 by means of a shaking and vibrating device. In place of magazine 54, each clamping device can also have a shaking and vibrating device which systematically supplies the connecting members to clamping device 28 from a nonsystematic store.

A hold down device 55 is arranged adjacent to and just behind each clamping device 28 relative to the direction of rotation D of rotary table 29. As can be seen in FIG. 12, hold down device 55 has a piston 156 in a cylinder 56 so that a pressure can act on both sides of the piston. The extending and retracting piston rod 256 can pivot a lever 57 about a pivot 58 from the horizontal position shown, into a vertical position shown by broken lines. Between a fork-like recess lever 57 is disposed a finger 59 which has a longitudinal projection which is counter to the tension of a tension spring 60.

Finger 59 can pivot outwards and downwards about pivot 61 in a pawl-like manner. However, its upward pivotal movement is limited in the direction of the longitudinal projections of lever 57 by a fork stem 157.

The hold down device has two functions. Its first function is to keep the connecting member area of the clamping device free from barbed connected barbed spiral convolutions (FIG. 12). Thus, whenever the clamping device 28 associated with the hold down device has connected to the barbed spiral convolutions and has returned to its initial position, the hold down device swivels from its vertical position, into its horizontal position so that finger 59 engages in the winding circle of reel 24 and presses the two barbed spiral convolutions already connected in the connecting member plane downward on to the convolutions already connected in an earlier operation in order to form a dense layer of convolutions. i

The second function of the hold down device is to keep the upper barbed spiral convolution to ,be connected with the strip being fed in an advantageous spatial relationship relative to the connecting member plane of clamping device 28 (i.e., its collecting jaw.44 in FIG. 12) and relative to the strip being fed in, spaced from the already connected convolutions. As shown in FIG. 4, the barbed strip is wound onto the reel with a certain tensile stress, and the upper convolution to be connected with the strip being fed in is already connected to the penultimate convolution in front of and behind the connecting member point. Therefore, the upper convolution must be deflected upwards counter to the tensile stress in the connecting member plane. The hold down device fulfills this function, in that after the clamping device is moved back, and the two previously connected convolutions are moved downward, finger 59 remains in the winding cricle of the reel until two further convolutions have been placed over it and the clamping device has been extended for connecting these convolutions and the convolutions that have been received in collecting jaw 44. Then while the clamping device remains in its extended position where the connecting process is perfomied, the hold down device pivots outwardly and upwardly so that finger 59 is removed resiliently and radially from the winding circle of thereel as a result of its pawl-like mounting. In order to fulfill the described spacing function, finger 59 has a certain thickness as shown in FIG. 12.

The automatic machine operates in the following manner:

The already formed barbed strip, leaving rollers 22 at the beginning of a winding process, has its beginning point fixed at position 26 to reel 24. The reel is then extended further upwards so that position 26 is located in the connecting member plane. Clamping device 28 with its associated hold down device 55 on rotary table 29 closest to position 26, counter to rotation direction D, is designated I. The following clamping device with its holding downdevice is designated as II and so on until V. The timing diagram for clamping devices Z and hold down devices N is shown in FIG. 13. Clamping devices Z and hold down devices N are entered individually on the co-ordinate and the time in radians on the abscissa. The particular working cycle (in the case of the hold down device pivoting finger 59 into the winding circle of the reel, and in the case of the clamping device its extension of the legs) is shown in thick lines level with the associated member. Therefore at the start of the rotary movement, all the clamping devices are in the retracted inoperative position and hold down devices I, III and V are pivoted into the winding circle of the reel. The reel is then turned until slightly more than a complete convolution has been laid i.e.

until clamping device I has passed feed-in point 25. During this first rotation, hold down device II is also pivoted over the first convolution. During the following second rotation of the reel a connection occurs at points I, III and V together with the pivoting in of hold down device IV. During the third rotation, connection takes place at II and IV and so on.

The connecting order for the particular clamping device takes place in a rotation angle position just behind feed-in point 25, and the order for moving the clamping device back in a rotation angle position about 90 takes place in front of feed-in point 25. Therefore the connecting operation can take place during a period of a little more than 180 radians. Since a connecting process always takes place only at every other spacing point, a particular clamping device only has to perform a connecting operation once per two rotations. Since, apart from small time delays, the hold down devices pivot into the winding circle of the reel, and the associated clamping device moves back and pivots out of it when extended for performing a connecting process, and since the particular hold down device has to complete only one working cycle per two rotations, a hold down device remains pivoted into the winding circle of the reel for about 540 radians.

The control which does not form an object of the invention can take place in various ways e.g. in such a way that after the start of the strip is fixed to the reel, it is only necessary to give a single starting order. At the end of the winding process, a single stopping order is given so that all intermediate processes, particularly those after the first winding is completed take place automatically.

After each full rotation, reel 24 is automatically lowered by an amount corresponding to the height of one winding e.g. by mounting the reel with a threaded spindle. Thus, in spite of the increase in the number of windings on the reel, the uppermost winding laid by feed-in point remains in the correct relative position to the connecting member plane of clamping devices 28.

After a pre-determined number of windings are lowered, and after the final connecting member is fitted, the reel and strip feed are stopped. The strip portion fed in is cut off close to the final connecting member. The start of the strip is removed at point 26. All hold down devices are pivoted out while any not completely retracted clamping devices are completely retracted, and the finished barbed spirals are removed upwards from the reel. After the reel is raised to its starting position, a new winding cycle can commence.

While only a few embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.

What is claimed is:

1. A process for producing a barbed spiral from a flat metallic barbed strip having a series of barbs and a sup- -,.x: rting wire comprising the steps of:

winding v1 wire-supported strip in a spiral with successive convolutions wh' are juxtaposed in the longitudinal direction or spiral by feeding said strip onto a reel wherein the spiral has an odd number of connecting points uniformly distributed over the periphery of said spiral;

during the winding step, connecting said wire supported strip which is being fed to the reel with a 8 previously wound of said convolutions at a second next point of said odd number of connecting points, resulting in juxtaposed of said convolutions of said spiral being connected so that the spiral is extendable in a longitudinal direction in an accordian-like manner.

2. The process according to claim 1 wherein the supported barbed strip is wound up with its barbed strip surface at right angles to the spiral longitudinal axis whereby those portions of the barbed strip carrying the barbs cover one another in the longitudinal direction of the spiral and the connecting members are placed in the space between the barbed strip portions carrying the barbs.

3. An apparatus for producing a barbed spiral from a flat metallic barbed strip having a series of barbs and a supporting wire comprising:

a first supply feed for feeding a supporting wire;

a second supply feed for feeding the flat metallic strip;

envelope rollers receiving the strip and the wire and embedding the wire into the flat metallic strip;

a reel at the output of the envelope rollers for winding the wire supported strip in convolutions which are juxtaposed in the longitudinal direction of the spiral; and

connecting means for coupling connecting members on every other barb of adjacent convolutions of the spiral so that the spiral is extendable in a longitudinal direction in an accordion-like manner.

4. The apparatus according to claim 3 wherein said connecting means comprises a plurality of circumferentially spaced-apart clamping devices corresponding in number to the number of connecting points for connecting the convolutions of the spiral.

5. The apparatus according to claim 4 wherein each clamping device comprises a pair of legs having extending power arms, expanding levers having one end pivotably coupled to the power arms, a common fork coupled to the opposite ends of said levers, a piston having a piston rod connected to said common fork, a clamping head coupled to said pair of legs and including a collecting jaw for receiving a pair of convolutions of the barbed spiral, a compression spring tensioning the head with respect to the common fork, so that when a fluid under pressure is applied to one side of said piston, the pair of legs close a connecting member over a pair of convolutions and when the pressure is applied to the other side of the piston, the legs open to release the connecting member and are retracted.

6. The apparatus according to claim 4 additionally comprising a rotary table surrounding the reel and supporting said clamping devices, said table rotating synchronously with said reel.

7. The apparatus according to claim 6 comprising means for lowering the reel corresponding to the rise of the winding proportionally to the rotary table and the stationary output of the envelope rollers.

8. The apparatus according to claim 6 comprising fingers mounted on the rotary table between said clamping devices for pivoting into and out of the winding circle of said reel.

9. The apparatus according to claim 8 in which the pivoting in and out takes place in a plane containing the rotational axis of said reel.

10. The apparatus according to claim 9 wherein each finger is carried by a swivel arm and includes a spring catch with a top abutment so that upon swinging back,

13. The apparatus according to claim 3 wherein the winding capacity of the reel is an integral multiple of the spacing of the barbed strip portions carrying the barbs divided by the number of clamping devices.

14. The apparatus according to claim 3 wherein said reel is formed by coaxially positioned web ribs distributed over the periphery so that they engage in the gaps between the barbed strip portions carrying the barbs. 

1. A process for producing a barbed spiral from a flat metallic barbed strip having a series of barbs and a supporting wire comprising the steps of: winding the wire-supported strip in a spiral with successive convolutions which are juxtaposed in the longitudinal direction of the spiral by feeding said strip onto a reel wherein the spiral has an odd number of connecting points uniformly distributed over the periphery of said spiral; during the winding step, connecting said wire supported strip which is being fed to the reel with a previously wound of said convolutions at a second next point of said odd number of connecting points, resulting in juxtaposed of said convolutions of said spiral being connected so that the spiral is extendable in a longitudinal direction in an accordian-like manner.
 2. The process according to claim 1 wherein the supported barbed strip is wound up with its barbed strip surface at right angles to the spiral longitudinal axis whereby those portions of the barbed strip carrying the barbs cover one another in the longitudinal direction of the spiral and the connecting members are placed in the space between the barbed strip portions carrying the barbs.
 3. An apparatus for producing a barbed spiral from a flat metallic barbed strip having a series of barbs and a supporting wire comprising: a first supply feed for feeding a supporting wire; a second supply feed for feeding the flat metallic strip; envelope rollers receiving the strip and the wire and embedding the wire into the flat metallic strip; a reel at the output of the envelope rollers for winding the wire supported strip in convolutions which are juxtaposed in the longitudinal direction of the spiral; and connecting means for coupling connecting members on every other barb of adjacent convolutions of the spiral so that the spiral is extendable in a longitudinal direction in an accordion-like manner.
 4. The apparatus according to claim 3 wherein said connecting means comprises a plurality of circumferentially spaced-apart clamping devices corresponding in number to the number of connecting points for connecting the convolutions of the spiral.
 5. The apparatus according to claim 4 wherein each clamping device comprises a pair of legs having extending power arms, expanding levers having one end pivotably coupled to the power arms, a common forK coupled to the opposite ends of said levers, a piston having a piston rod connected to said common fork, a clamping head coupled to said pair of legs and including a collecting jaw for receiving a pair of convolutions of the barbed spiral, a compression spring tensioning the head with respect to the common fork, so that when a fluid under pressure is applied to one side of said piston, the pair of legs close a connecting member over a pair of convolutions and when the pressure is applied to the other side of the piston, the legs open to release the connecting member and are retracted.
 6. The apparatus according to claim 4 additionally comprising a rotary table surrounding the reel and supporting said clamping devices, said table rotating synchronously with said reel.
 7. The apparatus according to claim 6 comprising means for lowering the reel corresponding to the rise of the winding proportionally to the rotary table and the stationary output of the envelope rollers.
 8. The apparatus according to claim 6 comprising fingers mounted on the rotary table between said clamping devices for pivoting into and out of the winding circle of said reel.
 9. The apparatus according to claim 8 in which the pivoting in and out takes place in a plane containing the rotational axis of said reel.
 10. The apparatus according to claim 9 wherein each finger is carried by a swivel arm and includes a spring catch with a top abutment so that upon swinging back, its swivel arm can fall back and remain on the barbed strip.
 11. The apparatus according to claim 8 wherein said fingers are arranged in close proximity behind each clamping device in the rotational direction.
 12. The apparatus according to claim 3 comprising drive means coupled to said reel and said envelope rollers so that the reel rotates slightly faster than the envelope rollers causing the strip to slip on the reel.
 13. The apparatus according to claim 3 wherein the winding capacity of the reel is an integral multiple of the spacing of the barbed strip portions carrying the barbs divided by the number of clamping devices.
 14. The apparatus according to claim 3 wherein said reel is formed by coaxially positioned web ribs distributed over the periphery so that they engage in the gaps between the barbed strip portions carrying the barbs. 